Ray Tracing

A rendering method that traces rays backward from the camera through reflections and refractions; highly realistic but slow.

Ray tracing is one of the two fundamental rendering approaches. It casts a ray from the camera through each pixel, finds which object it hits first, and continues tracing reflection, refraction, and shadow rays toward light sources, which naturally produces effects like mirror reflections, transparent refraction, and soft shadows. Path tracing is its more advanced form, letting rays bounce randomly many times to approximate global illumination — the most realistic and slowest option. Because it is computationally expensive, ray tracing was long confined to offline rendering such as film; real-time ray tracing only became practical after NVIDIA launched GeForce RTX graphics cards with dedicated RT cores (hardware that accelerates ray-surface intersection) in 2018, which is where the term “RTX rendering” comes from. The Omniverse RTX renderer used by Isaac Sim is based on path tracing, and sensor simulation for things like RTX lidar depends on it too. In embodied AI, ray tracing generates photorealistic synthetic data and simulates transparent and reflective objects to narrow the visual sim-to-real gap, at the cost of being much slower than rasterization.

ExampleRendering a glass filled with water in path-tracing mode inside Isaac Sim produces near-camera-realistic refraction and highlights, useful for training a grasping model to recognize transparent objects.

Also called

Ray-Traced Rendering, RTX Rendering

Related

Rendering · Rasterization · Path Tracing · Photorealistic Rendering · NVIDIA Isaac Sim · Sensor Simulation

Sources

Wikipedia: Ray tracing (graphics)
Omniverse 文档：RTX Renderer（Real-Time 2.0 / Interactive Path Tracing） (Chinese)
NVIDIA Blog: What's the Difference Between Ray Tracing and Rasterization?

As of

2026-09